18G4.] 269 



Legs yellowish-rufous, the four anterior eosre and trochanters pale yel- 

 lowish, the posterior tibiae and tarsi obfuscated. Abdomen long and 

 slender, black, shining at tip ; apical margins of the 1st, 2nd and 4th 

 segments and the apical half of the 3rd segment, pale rufous, that on 

 the 4th segment obscure. Length 3 lines ; expanse of wings 4 lines. 

 Hah. — Delaware. Dr. Thos. B. Wilson. 



24. Mesoleptus flavifrons. n. sp. 



Black : face, mouth, spot on each side of mesothorax, tegulre and four ante- 

 rior coxse, yellow; legs and abdomen, except base, honey-yellow; wings large, 

 hyaline, areolet subtriangular, oblique ; subpetiolated ; abdomen clavate. 



Male. — Head black, shining; the face beneath the antennae, clypeus, 

 mandibles and palpi, yellow ; antennae very slender, longer than the 

 body, brown-black, paler towards the tips, the two basal joints beneath 

 yellowish. Thorax black, shining; a spot on each side of the meso- 

 thorax anteriorly, tegulge, and small spot before and another beneath 

 the fore-wings, yellow ; scutellum convex, black ; metathorax black, 

 shining, almost smooth, without elevated lines, except a few longitudinal 

 rugae on the disk. Wings long and ample, hyaline, beautifully iride- 

 scent ; nervures fuscous, pale testaceous at base, stigma black, with an 

 obscure pale spot at base ; areolet subtriangular, slightly oblique and 

 subpetiolated, the 2nd recurrent nervure somewhat angular in the mid- 

 dle. Legs honey-yellow, the four anterior coxa3 and all the trochanters, 

 pale yellowish; tips of the posterior tibife black. Abdomen clavate, 

 slender at base ; 1st segment sublinear, slender, slightly dilated at tip, 

 with a rather prominent tubercle on each side of the middle ; the seg- 

 ments gradually dilated from the 2nd segment to the tip ; basal segment 

 black, its tip and all the remaining segments honey -yellow ; beneath 

 paler. Length 3 J lines; expanse of wings 62 lines. 



Hah. — New Jersey. E, T. Cresson. 



25. Mesoleptus bicolor, n. sp. 



Black ; mouth, antennae, legs and abdomen dull honey-yellow ; wings hya- 

 line, areolet oblique, subpetiolated; abdomen slightly petiolated, subclavate. 



Male. — Head black, anterior margin of the clypeus and most of man- 

 dibles rufo-testaceous ; palpi whitish ; antennae very slender, longer 

 than the body, dull honey-yellow. Thorax black ; tegulas whitish ; scu- 

 tellum and metathorax black, the elevated lines of the latter subobso-. 

 lete. Wings ample, hyaline, iridescent; nervures fuscous, pale testa- 



